A conventional thin film fuse for a silicon integrated circuit has a structure as shown in FIG. 3 wherein reference numeral 41 designates a silicon substrate, reference numeral 42 designates a thin film fuse, reference numeral 45 designates a field insulating layer consisting of silicon oxide, reference numeral 47 designates an inter-layer insulating layer and reference numeral 48 designates a protective insulating layer consisting of a phosphor-doped silicon oxide.
The total thickness of the inter-layer insulating layer 47 and the protective insulating layer 48 is relatively large, being in the order of about two micrometers. Accordingly, the thin film fuse 42 occasionally exhibits a poor heat-radiation property when it opens upon application of an electric current thereto, and consequently the silicon substrate 41 melts instantaneously or the field insulating layer 47 cracks. Especially, when the thin film fuse 42 is made of a high melting point metal, the temperature at which the fuse opens becomes so high that the above-mentioned tendency is accelerated.